Small diameter sausages such as frankfurters or the like usually are made using food casings of cellulose. Cellulose food casings or the like customarily are manufactured in long continuous tubular lengths. For handling convenience, these long tubular lengths are gathered into pleats by shirring and are longitudinally compressed by known techniques to obtain a shorter, relatively rigid tubular element known in the industry as a shirred casing stick. The coherency of a shirred stick is derived in part from the shirring operation which forms the casing into generally conical pleats which nest one within another.
During a stuffing operation the stick is loaded onto a stuffing horn and a food emulsion is fed through the horn and into casing which is drawn forward from the stick by the stuffing pressure. It is not uncommon for a shirred stick 50 cm long to contain upwards of 50 meters or more of casing so a large number of individual frankfurters are made with each stick.
Packaging and shipping of shirred sticks presents several problems particularly for the type of casings used for frankfurters which generally have a wall thickness of only about 0.025 to about 0.05 mm. For example, shirred sticks of this casing are relatively fragile in that the nested pleats of casing formed by the shirring operation are easily separated or pulled apart. If the pleats separate, the stick is said to break or lose "coherency". The result is one or more rigid shirred sections connected by loose unshirred sections. Sticks in this condition are not easily loaded onto a stuffing horn and are not at all suitable for automatic stuffing operations wherein the stick is loaded onto a stuffing horn by mechanical means. Accordingly, the packaging for the shirred sticks must be able to minimize stick breakage.
Shirred sticks also are susceptible to damage if made wet. Since stuffing machines frequently are hosed down with water after a stuffing operation, any sticks in the area must be retained in packaging which provides a barrier to water spray and is not itself damaged by water contact.
In commercial practice it generally is customary to package sticks in tight bundles of fifty (50) sticks. Bundling sticks together accomplishes several functions. For example, if the sticks are tight together, there is less likelihood of relative motion between the sticks so the sticks do not rub one against another. Rubbing together of sticks tends to produce undesirable pinhole damage in shirred casing. Also, a tight bundle helps to prevent bowing of individual sticks. Bowing is the result of a number of factors known in the art and is cause for concern because a bowed stick may not load onto a stuffing horn. A tight bundle further tends to reduce the likelihood of stick breakage as long as the bundle remains intact.
Conventional packaging for retaining a stick bundle generally is a carton or box comprising a combination of corrugated fiber board and a plastic wrap such as a shrink or stretch wrap. Packages of this type are substantially rigid and are recloseable so unused sticks remaining after a stuffing operation can be returned to the carton. Thus, if the stuffing operation consumes fewer than fifty sticks, the unused remaining sticks are usually loosely laid back into the package. However, the returned sticks which are loose in the carton may rub together when moving the carton and this in turn can cause pinhole damage. Also, the carton, when partly filled, takes up the same space as a full carton due to the rigidity of the corrugated fiber board. Corrugated fiber board has the further drawbacks of adding bulk and the expense to the packaging and unless it is treated, the material is susceptible to water damage. In another packaging system as shown in U.S. Pat. No. 3,764,351, ridge end panels are placed against the end of the stack and then the stack is bundled together with the rigid end panels by a shrink film. The integrity of the resulting package is destroyed when the film is torn for opening the package.
Shirred sticks are sold in a number of different diameters and lengths. While packages of fifty sticks are most common, counts of less than fifty sticks are usual for certain sizes of casings. Accordingly, different sizes of cartons and/or carton components must be kept in inventory to provide the appropriate packaging for a given number of each particular size (diameter and length) of stick. The need to obtain and stockpile carton or carton components in a variety of sizes adds to the packaging costs.
The present invention provides an inexpensive package and method which maintains the integrity of a bundle of shirred casing sticks without use of bulky corrugated fiberboard or the like. Moreover, in a preferred embodiment, the package of the present invention is rigid enough that the package retains its shape after sticks are removed so that unused sticks are easily returned to the package. The package also is flexible so that it can be collapsed about a less than full bundle of sticks.
In its collapsed condition, the package occupies less space than it does when it contains a full stick count. Also, in its collapsed condition, the package is able to press inward on the few remaining sticks. This maintains the integrity of a bundle formed with less than the full stick count and provides resistance to breakage.
The package further provides protection from water spray, is easily formed, and has a top which is easy to open and close so sticks are easily removed from, or returned to, the package. Moreover, the packaging of the present invention eliminates the need to stock container components of different sizes because the container for shirred sticks as disclosed herein is made from a single sheet of stretch film.
The package of the present invention is obtained by assembling a bundle of casing sticks and then forming a container insitu about the bundle from a heat shrinkable film. A sheet of the film is wrapped about the bundle so opposite ends of the sheet overlap at the top of the bundle and the side margins of the sheet drape over the ends of the bundle. Upon heat shrinking the film draws tight about the bundle and the draped side margins weld together to form the ends of a container. The heat shrink film forms to the bundle shape and after heat shrinking it is sufficiently rigid to be self supporting so it maintains this shape even after all sticks have been removed. The set shape of the heat shrunk film facilitates the return of unused sticks into the package. Then, after unused sticks are returned, the package can be collapsed and wrapped about the remaining stick so the repackaged sticks are bundled together and occupy a minimum of space. If a film such as a polyethylene film is used, it is likely that as a result of heat shrinking, the draped side margins of the sheet will become tacky and weld together to form the upstanding ends of the container.
It is preferred that the package be easy to open. Accordingly, in the course of heat shrinking the film about the bundle of sticks, the overlapped opposite ends of the film at the top of the bundle should not weld together. When using a heat shrink material which may weld to itself on heating, it may be necessary to provide insulation along the sheet ends to prevent such welding. Also the degree of heat shrinking should be controlled so the sheet ends do not draw away from each other and create a gap between them. As a result, the unwelded overlapped ends form flaps of at least partly unshrunk film at the top of the bundle which can be folded back to provide access to the sticks within the package without otherwise destroying the integrity of the insitu formed container.
Since it is preferred that the opposite ends of the sheet not be welded together, an adhesive tape of the like is applied prior to heat shrinking to hold the overlapped sheet ends together. This will insure that the overlapped ends do not pull apart so the film shrinks tightly about the sticks in the bundle. Also, the tape may itself provide sufficient insulation to prevent welding together of the overlapped ends. Further, the adhesive tape is easily removed and reapplied to permit repetitive opening and resealing of the flaps. The tape also can be used to hold a collapsed container in a position wrapped tightly about unused sticks.
Accordingly, the present invention is characterized in one aspect thereof by a shirred food casing package comprising
a) a bundle of tubular shirred sticks of food casing all of substantially equal length and diameter arranged in a plurality of rows stacked one on another with the longitudinal axes of said sticks parallel and the stick ends coplanar; PA1 b) said bundle disposed in an insitu formed container which substantially encloses the bundle, said container having an integral bottom, front and rear panels and a top all formed insitu about said bundle of a heat shrunk film wrapped around said bundle in a direction transverse the longitudinal axes of said sticks; PA1 c) said film having a width greater than the length of said bundle, each longitudinal side margin of said film being folded over against an end of said bundle and stiffened by heat shrinking to form said upstanding opposite end walls; PA1 d) said film having a length sufficient to extend about the perimeter of said bundle and the opposite ends of said film defining flaps which form said container top and said flaps being relatively unshrunk, unwelded and releasable one from another to provide means for opening and closing said top; PA1 e) an adhesive tape applied prior to heat shrinking for holding said flaps together; and PA1 f) said film shrinking and stiffening on heat shrinking to a shape conforming to the shape of said bundle, and said container retaining substantially said shape upon removal of sticks from said bundle through said top. PA1 a) arranging the shirred sticks in a plurality of rows stacked one on another to form the bundle with the longitudinal axes of the sticks in the bundle being parallel and with the stick ends being coplanar, the coplanar stick ends defining the ends of the bundle; PA1 b) wrapping a heat shrinkable film around the bundle in a direction transverse the longitudinal axes of the sticks, said film having a length sufficient to extend about the perimeter of said bundle and a width greater than the bundle length; PA1 c) bringing the opposite ends of the film together at a top of the bundle and folding each longitudinal side margin of the film over an end of the bundle; PA1 d) applying an adhesive tape to hold said film opposite ends together; PA1 e) heating the film to induce shrinking and stiffening of the film thereby forming a container insitu about the bundle which container has a shape determined by the shape of the bundle, and causing, by said heating, the stiffening of the folded over film side margins; and PA1 f) insulating the film opposite ends during said heating to at least partly avoid shrinking the film ends and preventing the welding of one of the film opposite ends to another whereby the film opposite ends at the top of the bundle remain releasable one from the other and define flaps which open to provide a reclosable access to the sticks within the insitu formed container.
In another aspect the invention is a method for forming a shirred food casing package comprising the steps of